Navegando por Orientadores "COSTA, Marcos Benedito Caldas"

Agora exibindo 1 - 9 de 9

Acesso aberto (Open Access)
Análise comparativa do desempenho da compensação da dispersão em redes de fibras ópticas
(Universidade Federal do Pará, 2019-12-13) LUZ, Fabrício Pinho da; COSTA, Marcos Benedito Caldas; http://lattes.cnpq.br/7636226766852440
Este trabalho aborda o uso de métodos para tratamento da dispersão em fibras ópticas, mostrando a eficácia da utilização para um melhor resultado do Fator de qualidade (Q. Factor) e da taxa de erro de bit (Min. Ber) na transmissão de dados por redes de fibras ópticas. Desse modo, esta dissertação tem por objetivo fazer uma análise do desempenho de uma das técnicas de Pós-compensação em sistemas Multiplexação por Divisão de Comprimento de Onda Densa, baseado em redes ópticas passivas (DWDM-PON) com 16 canais e 100GHz de espaçamento para uma taxa de transmissão de dados de 10Gbps através do método de Pós-compensação de dispersão; propõe a utilização de técnicas de dispersão, a de Pós-compensação e a de dispersão Cromática na transmissão de dados por fibras ópticas com utilização de fibras compensadoras de dispersão (DCF) e Fibras de Grade de Bragg (FBG) para um melhor resultado do fator de qualidade (Q-Factor) e da taxa de erro de bit (Min Ber). A metodologia aplicada teve base em levantamentos bibliográficos de trabalhos na mesma linha de pesquisa sobre métodos de tratamento dos efeitos não lineares, em especial o de dispersão em fibras ópticas; em seguida foi feita a modelagem da rede óptica no software OptiSytem da Optiwave Corporation para implementação das simulações dos métodos utilizados para tratamento da dispersão em fibras ópticas. Concluiu-se, a partir do estudo de três sistemas de compensação de dispersão, onde uma ligação DCF e uma ligação FBG foram utilizadas para esse fim, que os valores do fator Q e do BER foram comparados e analisados a uma taxa de transmissão de 10 Gb/s; que o fator Q e o OSNR para o sistema de compensação de simétrica (mista) eram os maiores, estas técnicas de compensação de dispersão diminuem a degradação do sinal, melhorando a transmissão dos dados no sistema, com fibra DCF as perdas totais aumentam devido os efeitos não lineares, e seu custo é maior do que a fibra FBG, ou seja, com fibra FBG, o custo do sistema é menor, porém seu alcance é limitado. Portanto as duas técnicas podem ser utilizadas dependendo dos requisitos da rede do projeto de telecomunicações.
Acesso aberto (Open Access)
Análise de desempenho deum sistema óptico baseado em interferômetro de Mach-Zehnder e amplificador óptico semicondutor
(Universidade Federal do Pará, 2024-11-18) ARAÚJO, Fábio Souza de; COSTA, Marcos Benedito Caldas; http://lattes.cnpq.br/7636226766852440
The present work introduces and explores, using the OptiSystem software, the performance of an optical system that combines the Mach-Zehnder interferometer, the semiconductor optical amplifier (SOA), and the Fiber Bragg Grating (FBG). The system is composed of three main parts: the transmission section, the semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) section, and the reception section. The performance parameters analyzed include the quality factor (Q-Factor) and the bit error rate (BER) for different bit sequences and variations in the optical fiber length. Overall, the proposed system demonstrated good performance, proving to be a viable design for metropolitan networks with links up to 50 km.
Acesso aberto (Open Access)
Análise e desempenho de um acoplador baseado em cristal fotônico dopado com érbio
(Universidade Federal do Pará, 2018-04-13) MARTINS, Elizete Sabino; COSTA, Marcos Benedito Caldas; http://lattes.cnpq.br/7636226766852440
In this dissertation, the concepts of photonic crystal were used to design an Erbium-doped photonic crystal coupler in order to verify the switching performance for the bar and cross states of the doped device in relation to the non-doped device. The Erbium-doped Photonic crystal coupler used the non-linear resonance caused by the excitation of the erbium ions located in the central row of a Photonic Crystal directional coupler. Such excitation causes the transition of the erbium ions from the ground state to the metastable state by amplifying the signal when the photons absorb the light emitted by the signal. The simulations occurred in the COMSOL Multiphysics® software, which uses the Finite Element Method (FEM). A comparative analysis was performed between a directional coupler of photon crystal doped with erbium and another non-doped. It was verified the switching performance of both from the normalized frequencies variation and it was verified that the doped coupler was able to operate in the barrra and cross states with the higher frequency spectrum.
Acesso aberto (Open Access)
Análise teórica de filtros em estruturas EBG e em guias de ondas de cristais fotônicos
(Universidade Federal do Pará, 2016-11-25) SOUSA, Fiterlinge Martins de; COSTA, Marcos Benedito Caldas; http://lattes.cnpq.br/7636226766852440
This paper presents simulations of a band-stop filter using microwave Electromagnetic Bandgap structures (EBG). In the filter structure are made holes in the ground plane and these holes will subsequently changed its diameter to improve the rejection band of the quality and obtaining two rejection bands. Compared with conventional filters, filters with EBG structures have better rejection bandwidth characteristics in the microwave band. These simulations were performed with commercial software ANSYS HFSS. A filter structure using photonic waveguides is also modeled and simulated using commercial software Comsol. The effects of the physical parameters of the structure in relation to the filter characteristic are studied in both filters. The results of the creation and simulation procedure are described and possible applications of these filter structures are discussed in this paper. The particularly wide stopband is achieved by the circuits presented in this paper as well as two rejection bands.
Acesso aberto (Open Access)
Estruturas photonic band gap em antena de microfita com aplicações em microondas e terahertz
(Universidade Federal do Pará, 2019-08-16) OLIVEIRA, Jorge Everaldo de; COSTA, Marcos Benedito Caldas; http://lattes.cnpq.br/7636226766852440
In this work we are analyzing the simulations of two microstrip antennas. The first is an antenna using the ceramic material Bismuth Niobate (BiNbO4) doped with Vanadium Pentoxide (V2O5) on the substrate. The antenna patch was designed with indented power line to facilitate matching of impedances and the substrate with air holes was placed just below the patch to further decrease the losses. The second is a nano-antenne with Graphene Patch in the Terahertz range and PBG (Photonic Band Gap) substrate with triangular mesh, and holes in the following height configurations h1, h2 and h3. At time h1 the substrate is fully drilled, while at heights h2 the holes will be made top to bottom of the substrate and the height h3 is the antenna with substrate drilled from the bottom up to the middle of the substrate. Therefore three antennas are created in these geometries using a triangular hole network. The arrangement of the holes in the dielectric substrate constitute the PBG structure, to increase the performance and efficiency of these antennas, extinguishing surface waves in the substrate of microstrip antennas. The adopted geometry also improves antenna parameters such as efficiency and bandwidth. The commercial software HFSS and CST were used for the simulations of the antennas. After the numerical simulation steps the results of the parameters of these devices were obtained. The first antenna (periodic lattice with ceramic substrate) obtained a return loss of -36.21 dB, at a resonance frequency of 10,26 GHz, with a bandwidth of 2.18 GHz. In the simulations of the antennas of microstrip with Patch of graphene the antenna h3 obtained double transmission band with chemical potential of graphene of 0,3 eV.
Acesso aberto (Open Access)
Obtenção e análise da performance de portas lógicas totalmente ópticas baseadas em guias de onda de cristais fotônicos
(Universidade Federal do Pará, 2016-09-09) ALMEIDA, Léo César Parente de; COSTA, Marcos Benedito Caldas; http://lattes.cnpq.br/7636226766852440
In this work, we used the concept of Photonic Crystals (PhCs) for the computational simulation of two all-optical logic gates, the NOT and NAND gates. These new all-optical structures consist of a Photonic Crystal Ring Resonator (PCRR) in two dimensions (2-D) made of dielectric rods silicon (Si) in air substrate. The Plane Wave Expansion (PWE) and the Finite Difference Time Domain (FDTD) methods are used to analyze the behavior of these structures. The PWE method is used to calculate the Photonic Band Gap (PBG) of the PhC structures, that is from 0.2654 to 0.3897 (a / λ). The square lattices of logic gates (NOT and NAND) designed are implemented on the operational wavelength of 1700 nm. The simulation results show that the proposed structures are potential candidates for the design of ultra-fast optical digital circuits and highly advantageous with high transmission power, simple design, and are strongly applicable to the manufacture of Photonic Integrated Circuits (PICs) due to their simple structure and its clear operating principle. KEYWORDS: All-Optical NOT Logic Gate, Photonic Crystal Ring Resonator, Finite Difference Time Domain, Contrast Ratio.
Acesso aberto (Open Access)
Portas lógicas totalmente ópticas baseado em interferômetro de Michelson com amplificador óptico semicondutor
(Universidade Federal do Pará, 2018-08-24) OLIVEIRA, Jackson Moreira; COSTA, Marcos Benedito Caldas; http://lattes.cnpq.br/7636226766852440
In this work, proposes all-optical logic gates device structure based on a Michelson interferometer (MI) composed of semiconductor optical amplifier (SOA) forming a structure of SOA-MI logic devices with symmetrically identical Fiber Bragg Grating (FBG) at the output of each of its arms, for numerical simulation of the all-optical AND, OR and NOR logic gates of two binary input signals with different bit numbers using the cross-gain modulation (XGM) technique at 10 Gb/s bit rate and filter bandwidth at 10, 20 and 40 GHz using OptiSystem 15.0 software by OptiWave Corporation, to demonstrate and extract simple design rules for high-speed optical processing and analysis of non-linear SOA-induced properties. In addition, this work includes the study of the effect of bandwidth and number of bits on received power, minimum bit error rate (BER), maximum quality factor (Q-factor), Optical Signal to Noise Ratio (OSNR) and optical spectrum, which demonstrates high-speed gates and performance. Were run the SOA-MI-based logic gates with some parameters and the results can demonstrate a structure of high-performance optical logic devices with high speed.
Acesso aberto (Open Access)
Projeto de um demultiplexador de cristal fotônico bidimensional baseado em grafeno para aplicação em sistemas por divisão de comprimento de onda (WDM).
(Universidade Federal do Pará, 2024-03-15) SILVA, Alan dos Reis; COSTA, Marcos Benedito Caldas; http://lattes.cnpq.br/7636226766852440
This work presents an eight-channel 2D photonic crystal demultiplexer based on graphene for application in optical systems that use the wavelength division multiplexing technique - WDM. The optical device was designed based on a square crystalline lattice of silicon dielectric rods immersed in air and is formed by three main parts: Bus waveguide; Octagonal resonator rings and L-curve waveguides. The COMSOL multiphysics software and the Legumes python packages were used to study and simulate the designed structure. In analyzing the simulation results, the resonant wavelength, spectral width, quality factor, transmission efficiency, spacing between channels and the level of electromagnetic interference (Crosstalk) for the eight channels of the demultiplexer were evaluated. Furthermore, the analysis of the results occurred from two different perspectives, in the first of which the relationship between the transmission parameters of the demultiplexer with the variation in the chemical potential of graphene was analyzed and in the second the application of the device in WDM systems was explored. In general, the analyzes carried out proved to be considerable regarding the application of the photonic device in optical wavelength division multiplexing (WDM) systems.
Acesso aberto (Open Access)
Regenerador 3r totalmente óptico baseado em interferômetro de Mach-Zehnder de fibra de cristal fotônico altamente não linear
(Universidade Federal do Pará, 2017-05-26) SOUSA, Fabio Barros de; COSTA, Marcos Benedito Caldas; http://lattes.cnpq.br/7636226766852440
The present work aimed to investigate by means of numerical simulations, a device able to perform 3R regeneration (Re-amplifying, Re-timing and Re-shaping) fully propagated signal in an optical communication system for optical fiber with bit rate of 10 Gbit/s, the initial transmit power 0 dBm and wavelength of 1550 nm. As an ally to the regeneration process using dispersive and nonlinear effects of self-phase modulation (SPM), cross-phase modulation (XPM) and four-wave mixing (FWM) in a Mach-Zehnder Interferometer, whose one of the arms is composed of a Highly Nonlinear Photonic Crystal Fiber (HNL-PCF). The simulations were performed using OptiSystem commercial software of company canadian Optiwave Corporation. System performance was analyzed by comparing the values of the quality factor (Q-factor), of the bit error rate (BER), of optical spectrum and the optical signal-to-noise ratio (OSNR) optical signals are regenerated, before regenerated and degraded in the entrance and exit of the proposed system. Through this project, it was possible to obtain an efficient signal regeneration, with optimal values of OSNR, quality factor (Q-factor) and low bit error rate (BER).